Abstract
The starting Co(II) complexes of the general formulae. [CO(L-1)(2)]Cl-4 center dot 4H(2)O, [Co(L-1)Cl-2]Cl (L-1 =N-{[(allyl amino)thioxomethyl]hydrazinocarbonylmethyl}trimethylammonium chloride: ATHTC), [Co(L-2)Cl] Cl center dot 2H(2)O center dot(1/2)EtOH (L-2=N-{[(ethylamine)thioxomethyl]hydrazinocarbonylmethyl)trimethylammonium chloride; ETHTC) and [Co(L-3)Cl-2]Cl center dot 2EtOH (L-3=N-{[(phenylaminomethyl)thioxomethyl]hydrazinocarbonylmethyl}pyridinium chloride: PTHPC), were synthesized by the conventional chemical methods. Tribochemical reactions of the above mentioned Coll complexes obtained by chemical methods with KI afford novel Co-II and Co-III complexes with the general formulae [Co(L-1')I-3 center dot(1/2)EtOH]I, [Co-2(L-1')I-4]I center dot EtOH, [Co(L-2')I-2 center dot(3/2)EtOH]I, [Co-2(L-2')I-4(OEt)(2)(H2O)(2)]I center dot(1/2)EtOH and [Co(L-3')I-2 center dot H2O]I center dot 3H(2)O. The ligands (L-1', L-2' and L-3') formed by tribochemical reactions are quite similar to these of L-1, L-2 and L-3, except that the ionizable chloride ions in case of L-1, L-2 and L-3 are substituted by iodide ions in (L-1', L-2' and L-3'). The isolated solid Co-II and Co-III complexes have been characterized by elemental analyses, conductivities, spectral (IR, UV-vis, H-1 NMR) and magnetic measurements. The IR spectra of the starting Co-II complexes indicate that both L-1 and L-3 behave in bidentate manner coordinating via the carbonyl oxygen and NH2 groups, but L-2 behaves as a tridentate fashion coordinating via the carbonyl oxygen, azomethine (C=N-2) and SH groups with displacement of a hydrogen atom from the latter group. On the other hand, the IR spectra of the iodide Coll and Co-III complexes, synthesized by tribochemical reactions, suggest that L-1' b e haves only in a bidentate fashion via NH1 and CS groups. L-2' behaves either as bidentate ligand through NH1 and C-SH with deprotonation from the latter group or as a tetradentate ligand towards two cobalt ions via OH, C=N-2, C=N-1 and C-SH with displacement of a hydrogen atom from the latter group. Moreover, L-3' behaves in a tetradentate ligand, toward two cobalt ions via the carbonyl oxygen, NH2. NH1 and C-SH with displacements of a hydrogen atom from the latter group. The spectral and magnetic results suggest a tetrahedral geometry for all Co-II complexes prepared by conventional chemical methods. The diamagnetic nature for three of the five iodide complexes, prepared by tribochemical reactions, suggests the oxidation of Co-II to Co-III ion and the existence of low spin-octahedral geometry around the Co-III ion. Finally, the results of the rest of the iodide Coll complexes suggest either tetrahedral and/or high-spin octahedral geometry. (c) 2008 Elsevier B.V. All rights reserved.